Multiblade impeller

ABSTRACT

The multiblade impeller of the present invention comprises a main plate, a side plate having a suction port at a center thereof, and a large number of blades provided between the main plate and the side plate and extend in the radial direction in an arc form. The main plate and the side plate each have a large number of ridge portions, each extending in the radial direction in an arc form so as to coincide with the shape of the blade extending in the radial direction in an arc form. End portions of the blades are inserted in grooves formed inside the ridge portions of the main plate and the side plate and are fixed to the ridge portions by being bent.

INCORPORATION BY REFERENCE

This application is a continuation of application Ser. No. 11/757,439,filed on Jun. 4, 2007, now allowed, which claims the benefit of JapaneseApplication No. JP 2006-278531, filed Oct. 12, 2006 in the JapanesePatent Office, the contents of each of which are incorporated byreference into this application.

BACKGROUND OF THE INVENTION

The present invention relates to a multiblade impeller and, moreparticularly, to a multiblade impeller suitable for industrialmachinery, air conditioning equipment, and the like.

Conventionally, a multiblade impeller comprising a main plate, a sideplate and a plurality of blades generally has a fixing structure forfixing the blades to the main plate and side plate, in which projectingpieces provided at end portions of the blade are inserted in blademounting holes provided in flat portions of the main plate and sideplate, and the projecting pieces are bent to fix the blade to the mainplate and side plate so as to press the main plate and side plate down.

Regarding the fixing structure for fixing the blades to the main plateand side plate, the conventional multiblade impellers have beendisclosed, for example, in JP-A-60-93200, JP-A-8-319992 andJP-A-7-127598.

In the multiblade impeller disclosed in JP-A-60-93200, a blade fixinginsertion piece is provided in a joint portion between a blade and aside plate having a blade mounting hole, and the insertion piece isdeformed to pressingly fix the blade and the side plate.

In the multiblade impeller disclosed in JP-A-8-319992, a plastic orbrazing metal is filled in joint portions between a main plate/sideplate and a blade to fix the blade to the main plate and the side plate.

In the multiblade impeller disclosed in JP-A-7-127598, protrusions areprovided on side surfaces of a blade, and the protrusions are closelyfitted in fitting grooves in a main plate and a side plate to fix theblade to the main plate and the side plate.

In the general fixing structure of the above-described conventionalmultiblade impeller, when the main plate, side plate and blades arethin, a high fixing strength cannot be obtained, and hence sufficientreliability cannot be attained. Therefore, there is need to increasetheir thickness, which leads to an increase in cost.

Also, since the main plate, the side plate and the blades are of asimple plate shape, a rigidity necessary for an impeller cannot beobtained unless the thicknesses thereof are increased. As a resultthereof, there is a problem that the weight of the multiblade impellerincreases to affect performance of products in which such multibladeimpellers are used. In other words, since the multiblade impellergenerally repeats start and stop, it is desired to facilitate the startand stop of the multiblade impeller and hence to improve the performanceof the product in which the multiblade impeller is used by decreasingthe weight of the multiblade impeller, and further it is desired toimprove the reliability of the product in which the multiblade impelleris used by decreasing a load to be applied to driving system of themultiblade impeller. In particular, in recent years, since therotational speed control of the multiblade impeller has been implementedby an inverter, it is desired to improve the response of rotationalspeed control and hence to improve the performance of the product inwhich the multiblade impeller is used by decreasing the weight of themultiblade impeller.

In the above-described multiblade impeller disclosed in JP-A-60-93200,because of the fixing structure in which the blade fixing insertionpiece is provided in the joint portion between the blade and the sideplate having the blade mounting hole, and the insertion piece isdeformed to press the blade and the side plate, the blade fixinginsertion piece is needed, and also troublesome work for deforming theblade fixing insertion piece along the blade is necessary, which resultsin an increase in cost. In the multiblade impeller disclosed inJP-A-60-93200 as well, since the main plate, the side plate and theblades are of a simple plate shape, rigidity necessary for an impellercannot be obtained unless the thicknesses thereof are increased, so thatthe multiblade impeller disclosed in JP-A-60-93200 has a problem similarto that of the above-described general fixing structure.

In the above-described multiblade impeller disclosed in JP-A-8-319992,because of the fixing structure in which plastic or brazing metal isfilled in the joint portions between the main plate/side plate and theblade to fix the blade to the main plate and the side plate, the brazingmaterial is needed, and also troublesome work for filling the brazingmaterial in the joint portions is necessary, which results in anincrease in cost. In the multiblade impeller disclosed in JP-A-8-319992as well, since the main plate, the side plate and the blades are of asimple plate shape, rigidity necessary for an impeller cannot beobtained unless the thicknesses thereof are increased, so that themultiblade impeller disclosed in JP-A-8-319992 has a problem similar tothat of the above-described general fixing structure.

In the above-described multiblade impeller disclosed in JP-A-7-127598,although the blade can be closely fitted in the fitting grooves in themain plate and the side plate by the protrusions provided on the sidesurfaces of the blade, the main plate, the side plate and the blades aresubstantially of a simple plate shape. Therefore, rigidity necessary foran impeller cannot be obtained unless the thicknesses of the main plate,the side plate and the blades are increased, so that the multibladeimpeller disclosed in JP-A-7-127598 has a problem similar to that of theabove-described general fixing structure.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above-describedproblems, and accordingly an object thereof is to obtain a multibladeimpeller having a main plate and a side plate having high fixingstrength between the main plate/side plate and the blades and highrigidity, which is low in cost, light in weight, and moreover high inreliability, and capable of improving the performance of a product inwhich the multiblade impeller is used.

To achieve the above object, the present invention provides a multibladeimpeller comprising a main plate, a side plate having a suction port ina center thereof, and a large number of blades that are provided betweenthe main plate and the side plate and extend in a radial direction in anarc form, wherein the main plate and the side plate each has a largenumber of ridge portions extending in the radial direction in an arcform so as to coincide with the shape of the blade extending in theradial direction in an arc form; and end portions of the blades areinserted in grooves formed inside of the ridge portions of the mainplate and the side plate, and are fixed to the ridge portions by beingbent.

More favorable specific configuration examples of the present inventionare as follows:

(1) The end portions of the blade are fixed in the ridge portions of themain plate and the side plate by being bent together with the ridgeportions.

(2) The ridge portions of the main plate and the side plate have aplurality of locking holes positioned at top portions thereof andprovided in the radial direction, and the end portions of the bladeshave a plurality of locking projecting pieces that pass through thelocking holes to be bent, and are fixed to the ridge portions in contactwith the locking holes and inlet sides of the grooves.

(3) A gap is provided between a tip end portion of the lockingprojecting piece provided in the end portion of the blade and the mainplate/the side plate.

(4) The plurality of locking projecting pieces in the end portion of theblade that are caused to pass through the locking holes in the ridgeportion are bent in opposite directions to each other.

(5) The shape on an inside diameter side of the blade is made a straightline connecting a position of the groove of the main plate to a positionof the groove of the side plate.

(6) A reinforcing rib is formed at a place at which the blade overhangsfarthest from the straight line connecting the position of the groove ofthe main plate to the position of the groove of the side plate on theinside diameter side of the blade.

(7) Longitudinal and transverse reinforcing ribs are formed in theblade.

(8) A hub is provided at a central portion of the main plate, caulkingconvex portions are provided in the hub, slits are provided in the mainplate, the main plate is press fitted into the caulking convex portionsof the hub and the caulking convex portions are crushed so that the huband the main part is joined.

According to the present invention configured as described above, therecan be obtained a multiblade impeller having a main plate and a sideplate having a high fixing strength between the main plate/side plateand blades and high rigidity, which is low in cost, light in weight, andmoreover high in reliability, and capable of improving the performanceof a product in which the multiblade impeller is used.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a multiblade impeller in accordance witha first embodiment of the present invention;

FIG. 2 is an enlarged sectional view of a fixing portion between a mainplate/side plate and a blade of the first embodiment;

FIG. 3 is a sectional view of a part, showing a shape of a blade of thefirst embodiment;

FIG. 4 is a perspective view of a multiblade impeller in accordance witha second embodiment of the present invention;

FIG. 5 is an enlarged sectional view of a fixing portion between a mainplate/side plate and a blade of the second embodiment;

FIG. 6 is a sectional view of a part, showing a shape of a blade of amultiblade impeller in accordance with a third embodiment of the presentinvention;

FIG. 7 is a sectional view of a part, showing the shape of a blade of amultiblade impeller in accordance with a fourth embodiment of thepresent invention;

FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 7;

FIG. 9 is a sectional view of a part, showing the shape of a blade of amultiblade impeller in accordance with a fifth embodiment of the presentinvention;

FIG. 10 is a perspective view of a hub of a multiblade impeller inaccordance with a sixth embodiment of the present invention;

FIG. 11 is a sectional view taken along the line XI-XI in FIG. 10; and

FIG. 12 is an enlarged view of portion A in FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described withreference to the accompanying drawings. The same reference numerals inthe drawings of the embodiments denote the same or equivalent elements.

A multiblade impeller in accordance with a first embodiment of thepresent invention is described with reference to FIGS. 1 to 3. FIG. 1 isa perspective view of a multiblade impeller 10 in accordance with thefirst embodiment of the present invention, FIG. 2 is an enlargedsectional view of a fixing portion between a main plate/side plate and ablade of the first embodiment, and FIG. 3 is a sectional view of a part,showing the shape of the blade of the first embodiment. The multibladeimpeller 10 in this first embodiment is an example of multibladeimpeller used for a turbofan.

The multiblade impeller 10 comprises a main plate 1, a side plate 2having a suction port 2 c at a center thereof, a large number of blades3 that are provided between the main plate 1 and the side plate 2 andextend in the radial direction in an arc form, and a hub 4 attached to acentral part of the main plate 1. By the rotation of the multibladeimpeller 10, air is sucked from the suction port 2 c of the side plate2, and is blown out of an outer periphery of the blade 3.

The main plate 1 has a plurality of ridge portions 1 a each extending inthe radial direction in an arc form so as to coincide with the shape ofthe blade 3 extending in the radial direction in an arc form, and thenumber of ridge portions 1 a is equal to the number of blades 3. Theside plate 2 has a plurality of ridge portions 2 a each extending in theradial direction in an arc form so as to coincide with the shape of theblade 3 extending in the radial direction in an arc form, and the numberof ridge portions 2 a is equal to the number of blades 3.

End portions 3 a of the blade 3 are inserted in grooves 1 b and 2 bformed inside the ridge portions 1 a and 2 a of the main plate 1 and theside plate 2, respectively, and are fixed to the ridge portions 1 a and2 a by being bent. According to this configuration, since the endportion 3 a of the blade 3 is fixed to the ridge portion 1 a, 2 a havinghigher strength, high fixing strength can be obtained even if thethicknesses of the main plate 1, the side plate 2 and the blades 3 aredecreased, so that the multiblade impeller 10 can be made low in cost,light in weight, and moreover high in reliability. Also, since therigidity of the main plate 1 and the side plate 2 is increased by theridge portions 1 a and 2 a thereof, the thicknesses of the main plate 1and the side plate 2 can be decreased, so that the weight of themultiblade impeller 10 can be reduced. Thereby, it is possible tofacilitate the start and stop of the multiblade impeller 10 and hence toimprove the performance of a product in which the multiblade impeller isused, and further it is possible to improve the reliability of theproduct in which the multiblade impeller is used by decreasing a load tobe applied to a driving system of the multiblade impeller. In the casewhere the rotational speed of the multiblade impeller 10 is controlledby an inverter, the response of rotational speed control is improved,and hence the performance of the product in which the multibladeimpeller is used can be improved.

In this embodiment, the end portions 3 a of the blades 3 are fixed inthe ridge portions 1 a, 2 a of the main plate 1 and the side plate 2 bybeing inserted in the grooves 1 b, 2 b in a state in which the ridgeportions 1 a, 2 a are formed in a vertical state by press forming and bybeing bent together with the ridge portions 1 a, 2 a of the main plate 1and the side plate 2. By this configuration, a far higher fixingstrength between the main plate 1/side plate 2 and the blade 3 can beachieved.

Next, the multiblade impeller 10 in accordance with a second embodimentof the present invention is described with reference to FIGS. 4 and 5.FIG. 4 is a perspective view of the multiblade impeller 10 in accordancewith the second embodiment of the present invention, and FIG. 5 is anenlarged sectional view of a fixing portion between the main plate/sideplate and the blade of the second embodiment. The configuration of themultiblade impeller 10 of this embodiment is basically the same as thatof the multiblade impeller 10 of the first embodiment except the pointdescribed below, so that the duplicated explanation is omitted.

In the second embodiment, the ridge portions 1 a and 2 a of the mainplate 1 and the side plate 2 have a plurality of locking holes 2 d thatare positioned at top portions of the main plate 1 and the side plate 2and are provided in the radial direction. The end portions 3 a of theblades 3 have a plurality of locking projecting pieces 3 b that passthrough the locking holes 2 d and are bent, and are fixed to the ridgeportions 1 a, 2 a in contact with the locking holes 2 d and inlet sideof the grooves 2 b. By this configuration, high fixing strength and highrigidity can be obtained by simple work of bending the lockingprojecting pieces 3 b even if the thicknesses of the main plate 1, theside plate 2 and the blades 3 are decreased. Therefore, an advantagethat the multiblade impeller 10 can be made low in cost, light inweight, and moreover high in reliability can be achieved, whichadvantage is the same as that of the first embodiment.

Also, in the second embodiment, gaps are provided between tip endportions of the locking projecting pieces 3 b provided at the endportions 3 a of the blades 3 and the main plate 1/the side plate 2.Thereby, when the multiblade impeller 10 is rotated, the occurrence ofnoise, vibrations, and damage caused by the contact between the lockingprojecting pieces 3 b and the main plate 1/the side plate 2 can beprevented.

Further, in the second embodiment, the locking projecting pieces 3 b atthe end portions 3 a of the blades 3 that are caused to pass through thelocking holes 2 d in the ridge portions 1 a, 2 a are bent in thedirection opposite to each other. Thereby, a far higher fixing strengthbetween the main plate 1/side plate 2 and the blade 3 can be achieved.

Next, third to sixth embodiments of the present invention are describedwith reference to FIGS. 6 to 12. FIG. 6 is a sectional view of a part,showing the shape of the blade of the multiblade impeller in accordancewith the third embodiment of the present invention, FIG. 7 is asectional view of a part, showing the shape of the blade of themultiblade impeller in accordance with the fourth embodiment of thepresent invention, FIG. 8 is a sectional view taken along the lineVIII-VIII in FIG. 7, FIG. 9 is a sectional view of a part, showing theshape of the blade of the multiblade impeller in accordance with thefifth embodiment of the present invention, FIG. 10 is a perspective viewof the hub of the multiblade impeller in accordance with the sixthembodiment of the present invention, FIG. 11 is a sectional view takenalong the line XI-XI in FIG. 10, and FIG. 12 is an enlarged view ofportion A in FIG. 11. The configurations of the multiblade impellers 10of the third to sixth embodiments are basically the same as that of themultiblade impeller 10 of the first embodiment or the correspondingembodiment except the points described below.

In the third embodiment, to enhance the rigidity of the blade 3, theblade shape on the inside diameter side of the blade 3 is made an endface 3 c obtained by connecting a position of the groove of the mainplate 1 to a position of the groove of the side plate 2 by a straightline.

In the fourth embodiment, to enhance the rigidity of the blade 3, areinforcing rib 5 is formed at a place at which the blade shapeoverhangs farthest from the straight line connecting the groove positionof the main plate 1 to the groove position of the side plate 2 on theinner diameter side of the blade 3.

In the fifth embodiment, to further enhance the rigidity of the blade 3,the reinforcing ribs 5 are formed in the longitudinal and transversedirections of the blade 3.

In the sixth embodiment, as shown in FIG. 10, caulking convex parts 6are provided on the hub 4, the caulking convex parts 6 are press fittedin slits 1 c formed in the main plate 1, and the caulking convex parts 6are crushed as shown in FIGS. 11 and 12. Thereby, a strong joiningbetween the main plate 1 and the hub 4 can be obtained.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

1. A multiblade impeller comprising a main plate, a side plate having asuction port at a center thereof, and a plurality of blades that areprovided between the main plate and the side plate and extend in aradial direction in an arc form, wherein the main plate and the sideplate each have a plurality of ridge portions extending in the radialdirection in an arc form so as to coincide with the shape of the bladesextending in the radial direction in an arc form; and end portions ofthe blades are inserted in grooves formed inside the ridge portions ofthe main plate and the side plate, and wherein the ridge portions of themain plate and the side plate have a plurality of locking holespositioned at top portions thereof and provided in the radial direction,the end portions of the blades have a plurality of locking projectingpieces that pass through the locking holes and are bent, and the endportions of the blades are fixed to the ridge portions and are incontact with the locking holes and the inlet sides of the grooves. 2.The multiblade impeller according to claim 1, wherein gaps are providedbetween tip end portions of the locking projecting pieces provided atthe end portions of the blades and the main plate, and gaps are providedbetween tip end portions of the locking projecting pieces provided atthe end portions of the blades and the side plate.
 3. The multibladeimpeller according to claim 1, wherein the plurality of lockingprojecting pieces at the end portions of the blades that are caused topass through the locking holes in the ridge portions are bent in adirection opposite to each other.
 4. The multiblade impeller accordingto claim 1, wherein at least one reinforcing rib is formed in eachblade, the at least one reinforcing rib not extending to an edge of eachblade.
 5. The multiblade impeller according to claim 1, whereinreinforcing ribs are formed in longitudinal and transverse directions ofeach blade.
 6. The multiblade impeller according to claim 1, wherein anumber of ridge portions on the main plate is equal to a number ofblades, and a number of ridge portions on the side plate is equal to thenumber of blades.
 7. A turbofan comprising the multiblade impeller ofclaim 1.